of environmental and seabird density variables by principal component analysis revealed seven components, explaining 71 % of the variance found in all variables. The most important components were: (1) a land–sea gradient combining hydrographic properties and distance to land/nearest colony; (2) tra...
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| Format: | Text |
| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.541.6400 http://icesjms.oxfordjournals.org/content/54/4/566.full.pdf |
| Summary: | of environmental and seabird density variables by principal component analysis revealed seven components, explaining 71 % of the variance found in all variables. The most important components were: (1) a land–sea gradient combining hydrographic properties and distance to land/nearest colony; (2) trawler abundance; and (3) a factor linked to water stratification and surface temperature. Distance to colony had a significant influence on the densities of all nine breeding species considered. Flight radii diVered considerably between the species. Densities in the vicinity of trawlers were particularly high in black-headed gulls (Larus ridibundus), herring gulls (L. argentatus), and great black-backed gulls (L. marinus). Black-headed gulls and herring gulls had the highest proportion of ship-followers of the total number of seabirds at sea; no ship-followers at all were found in Sandwich terns (Sterna sandvicensis), common/ Arctic terns (S. hirundo/paradisaea), or guillemots (Uria aalge). Surface salinity, transparency, and thermal stratification were apparently the most important hydro-graphic properties, characterizing distinct water masses. Cluster analysis revealed a group of four oVshore species (Fulmarus glacialis, Uria aalge, Rissa tridactyla, Larus fuscus) and seven inshore species (Larus ridibundus, L. canus, L. marinus, L. argentatus, Sterna sandvicensis, S. hirundo/paradisaea). Relations between important abiotic parameters and seabird diet are discussed. |
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